Vehicle seats are relatively complex structures including a combination of subsystems that may be used to position the seat, to provide heating and cooling, or to provide an adjustable lumbar support, in addition to providing a comfortable seating area for occupants. Most importantly, vehicle seats must provide a safe and comfortable seating area. Comfortable seating is increasingly important for drivers or passengers who spend extended time periods in a motor vehicle.
Various adjustable seat components are known which add to comfort. For illustration, an adjustable lumbar support structure may be integrated into the backrest of a vehicle seat. The adjustable lumbar support structure may be configured such that an amount of curvature and/or an apical position may be adjusted. In addition, massage functions may be provided in which different zones of the lumbar structure are displaced in a cyclical manner to produce a massage effect. Such lumbar support structures frequently include a flexible member which may be formed of a wire framework and/or a plastic member, suspended on a frame of the backrest.
A change in curvature and/or apex position or a massage function may be implemented in various ways. For illustration, plural traction members may be coupled to different zones of an adjustable component to selectively apply traction thereto. Bowden cables may be used as traction members, with the inner cable of the Bowden cable and the sheath of the Bowden cable being connected to the adjustable component and/or seat frame, such that a portion of the component can be displaced as a function of the free length of the inner cable which extends from the end of the sheath.
Traditionally, a separate actuator is provided for each Bowden cable. An example for such a configuration is described for example in WO 2006/105989 A1. While such a configuration provides a high degree of control over the traction applied to the different zones of the adjustable component, it may also require a significant amount of installation space in the backrest. Further, logic circuitry must be provided for controlling the different actuators in a coordinated manner, for example in order to implement a massage function. This adds to costs.
EP 1 762 155 A1 describes a support assembly in which the inner cables of two Bowden cables are connected to one actuator. Rotation of the actuator may cause one of the wires to be wound up and the other one to be unwound at the same time. A massage function can be realized by controlling the actuator so as to cyclically reverse its direction of rotation. For enhanced comfort, it may be desirable to provide an arrangement in which the number of zones that can be actuated can be easily increased.